The invention relates to the extraction of organic compounds from aqueous solutions of non-ionic surfactants.
Organic noxious compounds are present in the soil as liquids or solids or they are attached to soil particles (adsorbed). For soil reclamation, these organic compounds (noxious materials) can be washed out of the soils by using aqueous surfactant-containing solutions. As a result of such procedures, for example, aqueous solutions of non-ionic surfactants in which organic compounds are dissolved are present. In order to permitt the solutions of non-ionic surfactants to be reused the organic compounds must be extracted from the aqueous surfactants-containing solutions.
From the publication, J. L. Underwood, K. A. Debalak, D. J. Wilson, Sep. Sci-Technol. 1993, 28(9) 1647-1669 "SOIL CLEANUP BY IN-SITU SURFACTANT FLUSHING, VI RECLAMATION OF SURFACTANT FOR RECYCLE", it is known to extract organic substances (compounds) from ionic surfactants by way of liquid--liquid extraction. It is specifically pointed out that a liquid--liquid extraction is possible because exclusively solutions of ionic surfactants--but not solutions of non-ionic surfactants are employed.
It is well known in the field that non-ionic surfactants facilitate the formation of emulsions. It is also well known in the field that the separation of such emulsions is impossible or at least very expensive. It is furthermore well known that the formation of emulsions has disadvantageous effects on the liquid--liquid extractions. For this reason, the liquid--liquid extraction was considered by the state of the art to be possible only for solutions of ionic surfactants.
Nevertheless, inspite of the strong emulsion forming tendencies and the difficulties connected therewith, a liquid--liquid extraction of non-ionic surfactants from solutions was basically considered to be possible as apparent from the publication, K. Bankhoff, M. Wittmann, F. H. Haegel, G. Subklew, "EXTRAKTION VON POLYZYKLISCHEN AROMATISCHEN KOHLENWASSERSTOFFEN AUS BELASTETEN BODEN", published in Fremdstoffe in Boden--Akkumulation, Bioverfugbarkeit, Bewertungsansatze, Publisher: Arbeitsgemeinschaft der Grossforschungseinrichtungen (AGF), Bonn, 1994, 34-36. From this publication, it is not known however how such a liquid--liquid extraction of organic compounds from solutions of non-ionic surfactants is possible and whether such a process is economically feasible.
EP 0 432 651 A1 and DE 39 15 930 disclose the extraction of noxious materials by vegetable oils. However, there is no indication in these publications whether or how the solutions of non-ionic surfactants can be reclaimed.
It is the object of the present invention to provide an economically feasible method for the extraction of organic compounds from solutions of non-ionic surfactants, which permits particularly high volume processing.